Such devices are widely used. Reference to U.S. Pat. No. 5,452,339 is only made as an example in this case. It describes a course which ensures that no problems result from a defective change-over. The change-over possibility is stipulated in that case.
If a program-controlled device must be available practically without any interruption and still be able to be switched over to another operating system, it must be possible to reload the second program version during the operation and then switch over to it.
Processors which have an integrated solution for this problem can be found in the market. They also have other advantageous properties and are therefore respectively expensive. However, these other advantageous properties are not needed in every instance and the higher price is therefore not justified. The reloading of the new operating system into a still available memory area with its own address, and the subsequent change-over by considering this individual address are not feasible in practice, because a restart is never fully connected and different addresses cannot be taken into consideration during a restart. In contrast, the use of two switchable parallel memory blocks with the same addresses results in that the respectively inactive memory block cannot be addressed by the same processor and thus the reloading of the new operating system only becomes possible to a limited degree.